shithub: mc

ref: ebeb642003c6fdbf331968cff9d2e3d769fd6b02
dir: /lib/thread/queue.myr/

use std
use "mutex"
use "condvar"

pkg thread =
	type queue(@a) = struct
		hd	: qnode(@a)#
		tl	: qnode(@a)#
		mtx	: mutex
		cv	: cond
	;;

	type qnode(@a) = struct
		v	: @a
		next	: qnode(@a)#
	;;

	generic qinit	: (q : queue(@a)# -> void)
	generic qget	: (q : queue(@a)# -> @a)
	generic qput	: (q : queue(@a)#, v : @a -> void)
;;

generic Znode = (0 : qnode(@a)#)

generic qinit = {q
	q.hd = Znode
	q.tl = Znode
	q.mtx = mkmtx()
	q.cv = mkcond(&q.mtx)
}


generic qput = {q, v : @a
	var n : qnode(@a)#

	n = std.mk([.next=Znode, .v=v])
	mtxlock(&q.mtx)
	if q.hd == Znode
		q.hd = n
		q.tl = n
	else
		q.tl.next = n
		q.tl = n
	;;
	condsignal(&q.cv)
	mtxunlock(&q.mtx)
}

generic qget = {q
	var n, v

	mtxlock(&q.mtx)
:again
	if q.hd == Znode
		condwait(&q.cv)
		goto again
	else
		n = q.hd
		q.hd = q.hd.next
	;;
	mtxunlock(&q.mtx)
	v = n.v
	std.free(n)
	-> v
}